249 lines
7.9 KiB
C
249 lines
7.9 KiB
C
/* $NetBSD: cast128.c,v 1.9 2006/05/10 21:53:15 mrg Exp $ */
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/* $OpenBSD: cast.c,v 1.2 2000/06/06 06:49:47 deraadt Exp $ */
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/*
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* CAST-128 in C
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* Written by Steve Reid <sreid@sea-to-sky.net>
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* 100% Public Domain - no warranty
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* Released 1997.10.11
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*/
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#include <sys/cdefs.h>
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__KERNEL_RCSID(0, "$NetBSD: cast128.c,v 1.9 2006/05/10 21:53:15 mrg Exp $");
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#include <sys/types.h>
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#include <crypto/cast128/cast128.h>
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#include <crypto/cast128/cast128sb.h>
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/* Macros to access 8-bit bytes out of a 32-bit word */
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#define U_INT8_Ta(x) ( (u_int8_t) (x>>24) )
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#define U_INT8_Tb(x) ( (u_int8_t) ((x>>16)&255) )
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#define U_INT8_Tc(x) ( (u_int8_t) ((x>>8)&255) )
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#define U_INT8_Td(x) ( (u_int8_t) ((x)&255) )
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/* Circular left shift */
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#define ROL(x, n) ( ((x)<<(n)) | ((x)>>(32-(n))) )
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/* CAST-128 uses three different round functions */
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#define F1(l, r, i) \
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t = ROL(key->xkey[i] + r, key->xkey[i+16]); \
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l ^= ((cast_sbox1[U_INT8_Ta(t)] ^ cast_sbox2[U_INT8_Tb(t)]) - \
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cast_sbox3[U_INT8_Tc(t)]) + cast_sbox4[U_INT8_Td(t)];
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#define F2(l, r, i) \
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t = ROL(key->xkey[i] ^ r, key->xkey[i+16]); \
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l ^= ((cast_sbox1[U_INT8_Ta(t)] - cast_sbox2[U_INT8_Tb(t)]) + \
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cast_sbox3[U_INT8_Tc(t)]) ^ cast_sbox4[U_INT8_Td(t)];
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#define F3(l, r, i) \
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t = ROL(key->xkey[i] - r, key->xkey[i+16]); \
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l ^= ((cast_sbox1[U_INT8_Ta(t)] + cast_sbox2[U_INT8_Tb(t)]) ^ \
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cast_sbox3[U_INT8_Tc(t)]) - cast_sbox4[U_INT8_Td(t)];
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/***** Encryption Function *****/
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void cast128_encrypt(const cast128_key* key, const u_int8_t* inblock,
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u_int8_t* outblock)
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{
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u_int32_t t, l, r;
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/* Get inblock into l,r */
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l = ((u_int32_t)inblock[0] << 24) | ((u_int32_t)inblock[1] << 16) |
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((u_int32_t)inblock[2] << 8) | (u_int32_t)inblock[3];
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r = ((u_int32_t)inblock[4] << 24) | ((u_int32_t)inblock[5] << 16) |
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((u_int32_t)inblock[6] << 8) | (u_int32_t)inblock[7];
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/* Do the work */
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F1(l, r, 0);
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F2(r, l, 1);
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F3(l, r, 2);
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F1(r, l, 3);
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F2(l, r, 4);
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F3(r, l, 5);
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F1(l, r, 6);
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F2(r, l, 7);
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F3(l, r, 8);
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F1(r, l, 9);
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F2(l, r, 10);
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F3(r, l, 11);
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/* Only do full 16 rounds if key length > 80 bits */
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if (key->rounds > 12) {
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F1(l, r, 12);
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F2(r, l, 13);
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F3(l, r, 14);
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F1(r, l, 15);
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}
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/* Put l,r into outblock */
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outblock[0] = U_INT8_Ta(r);
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outblock[1] = U_INT8_Tb(r);
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outblock[2] = U_INT8_Tc(r);
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outblock[3] = U_INT8_Td(r);
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outblock[4] = U_INT8_Ta(l);
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outblock[5] = U_INT8_Tb(l);
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outblock[6] = U_INT8_Tc(l);
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outblock[7] = U_INT8_Td(l);
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/* Wipe clean */
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t = l = r = 0;
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}
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/***** Decryption Function *****/
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void cast128_decrypt(const cast128_key* key, const u_int8_t* inblock,
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u_int8_t* outblock)
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{
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u_int32_t t, l, r;
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/* Get inblock into l,r */
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r = ((u_int32_t)inblock[0] << 24) | ((u_int32_t)inblock[1] << 16) |
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((u_int32_t)inblock[2] << 8) | (u_int32_t)inblock[3];
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l = ((u_int32_t)inblock[4] << 24) | ((u_int32_t)inblock[5] << 16) |
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((u_int32_t)inblock[6] << 8) | (u_int32_t)inblock[7];
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/* Do the work */
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/* Only do full 16 rounds if key length > 80 bits */
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if (key->rounds > 12) {
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F1(r, l, 15);
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F3(l, r, 14);
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F2(r, l, 13);
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F1(l, r, 12);
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}
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F3(r, l, 11);
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F2(l, r, 10);
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F1(r, l, 9);
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F3(l, r, 8);
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F2(r, l, 7);
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F1(l, r, 6);
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F3(r, l, 5);
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F2(l, r, 4);
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F1(r, l, 3);
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F3(l, r, 2);
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F2(r, l, 1);
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F1(l, r, 0);
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/* Put l,r into outblock */
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outblock[0] = U_INT8_Ta(l);
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outblock[1] = U_INT8_Tb(l);
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outblock[2] = U_INT8_Tc(l);
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outblock[3] = U_INT8_Td(l);
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outblock[4] = U_INT8_Ta(r);
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outblock[5] = U_INT8_Tb(r);
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outblock[6] = U_INT8_Tc(r);
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outblock[7] = U_INT8_Td(r);
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/* Wipe clean */
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t = l = r = 0;
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}
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/***** Key Schedual *****/
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void cast128_setkey(cast128_key* key, const u_int8_t* rawkey, int keybytes)
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{
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u_int32_t t[4], z[4], x[4];
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int i;
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/* Set number of rounds to 12 or 16, depending on key length */
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key->rounds = (keybytes <= 10 ? 12 : 16);
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/* Copy key to workspace x */
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for (i = 0; i < 4; i++) {
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x[i] = 0;
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t[i] = z[i] = 0; /* XXX gcc */
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if ((i*4+0) < keybytes) x[i] = (u_int32_t)rawkey[i*4+0] << 24;
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if ((i*4+1) < keybytes) x[i] |= (u_int32_t)rawkey[i*4+1] << 16;
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if ((i*4+2) < keybytes) x[i] |= (u_int32_t)rawkey[i*4+2] << 8;
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if ((i*4+3) < keybytes) x[i] |= (u_int32_t)rawkey[i*4+3];
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}
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/* Generate 32 subkeys, four at a time */
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for (i = 0; i < 32; i+=4) {
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switch (i & 4) {
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case 0:
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t[0] = z[0] = x[0] ^ cast_sbox5[U_INT8_Tb(x[3])] ^
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cast_sbox6[U_INT8_Td(x[3])] ^ cast_sbox7[U_INT8_Ta(x[3])] ^
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cast_sbox8[U_INT8_Tc(x[3])] ^ cast_sbox7[U_INT8_Ta(x[2])];
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t[1] = z[1] = x[2] ^ cast_sbox5[U_INT8_Ta(z[0])] ^
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cast_sbox6[U_INT8_Tc(z[0])] ^ cast_sbox7[U_INT8_Tb(z[0])] ^
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cast_sbox8[U_INT8_Td(z[0])] ^ cast_sbox8[U_INT8_Tc(x[2])];
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t[2] = z[2] = x[3] ^ cast_sbox5[U_INT8_Td(z[1])] ^
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cast_sbox6[U_INT8_Tc(z[1])] ^ cast_sbox7[U_INT8_Tb(z[1])] ^
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cast_sbox8[U_INT8_Ta(z[1])] ^ cast_sbox5[U_INT8_Tb(x[2])];
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t[3] = z[3] = x[1] ^ cast_sbox5[U_INT8_Tc(z[2])] ^
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cast_sbox6[U_INT8_Tb(z[2])] ^ cast_sbox7[U_INT8_Td(z[2])] ^
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cast_sbox8[U_INT8_Ta(z[2])] ^ cast_sbox6[U_INT8_Td(x[2])];
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break;
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case 4:
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t[0] = x[0] = z[2] ^ cast_sbox5[U_INT8_Tb(z[1])] ^
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cast_sbox6[U_INT8_Td(z[1])] ^ cast_sbox7[U_INT8_Ta(z[1])] ^
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cast_sbox8[U_INT8_Tc(z[1])] ^ cast_sbox7[U_INT8_Ta(z[0])];
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t[1] = x[1] = z[0] ^ cast_sbox5[U_INT8_Ta(x[0])] ^
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cast_sbox6[U_INT8_Tc(x[0])] ^ cast_sbox7[U_INT8_Tb(x[0])] ^
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cast_sbox8[U_INT8_Td(x[0])] ^ cast_sbox8[U_INT8_Tc(z[0])];
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t[2] = x[2] = z[1] ^ cast_sbox5[U_INT8_Td(x[1])] ^
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cast_sbox6[U_INT8_Tc(x[1])] ^ cast_sbox7[U_INT8_Tb(x[1])] ^
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cast_sbox8[U_INT8_Ta(x[1])] ^ cast_sbox5[U_INT8_Tb(z[0])];
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t[3] = x[3] = z[3] ^ cast_sbox5[U_INT8_Tc(x[2])] ^
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cast_sbox6[U_INT8_Tb(x[2])] ^ cast_sbox7[U_INT8_Td(x[2])] ^
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cast_sbox8[U_INT8_Ta(x[2])] ^ cast_sbox6[U_INT8_Td(z[0])];
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break;
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}
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switch (i & 12) {
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case 0:
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case 12:
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key->xkey[i+0] = cast_sbox5[U_INT8_Ta(t[2])] ^ cast_sbox6[U_INT8_Tb(t[2])] ^
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cast_sbox7[U_INT8_Td(t[1])] ^ cast_sbox8[U_INT8_Tc(t[1])];
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key->xkey[i+1] = cast_sbox5[U_INT8_Tc(t[2])] ^ cast_sbox6[U_INT8_Td(t[2])] ^
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cast_sbox7[U_INT8_Tb(t[1])] ^ cast_sbox8[U_INT8_Ta(t[1])];
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key->xkey[i+2] = cast_sbox5[U_INT8_Ta(t[3])] ^ cast_sbox6[U_INT8_Tb(t[3])] ^
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cast_sbox7[U_INT8_Td(t[0])] ^ cast_sbox8[U_INT8_Tc(t[0])];
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key->xkey[i+3] = cast_sbox5[U_INT8_Tc(t[3])] ^ cast_sbox6[U_INT8_Td(t[3])] ^
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cast_sbox7[U_INT8_Tb(t[0])] ^ cast_sbox8[U_INT8_Ta(t[0])];
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break;
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case 4:
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case 8:
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key->xkey[i+0] = cast_sbox5[U_INT8_Td(t[0])] ^ cast_sbox6[U_INT8_Tc(t[0])] ^
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cast_sbox7[U_INT8_Ta(t[3])] ^ cast_sbox8[U_INT8_Tb(t[3])];
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key->xkey[i+1] = cast_sbox5[U_INT8_Tb(t[0])] ^ cast_sbox6[U_INT8_Ta(t[0])] ^
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cast_sbox7[U_INT8_Tc(t[3])] ^ cast_sbox8[U_INT8_Td(t[3])];
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key->xkey[i+2] = cast_sbox5[U_INT8_Td(t[1])] ^ cast_sbox6[U_INT8_Tc(t[1])] ^
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cast_sbox7[U_INT8_Ta(t[2])] ^ cast_sbox8[U_INT8_Tb(t[2])];
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key->xkey[i+3] = cast_sbox5[U_INT8_Tb(t[1])] ^ cast_sbox6[U_INT8_Ta(t[1])] ^
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cast_sbox7[U_INT8_Tc(t[2])] ^ cast_sbox8[U_INT8_Td(t[2])];
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break;
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}
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switch (i & 12) {
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case 0:
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key->xkey[i+0] ^= cast_sbox5[U_INT8_Tc(z[0])];
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key->xkey[i+1] ^= cast_sbox6[U_INT8_Tc(z[1])];
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key->xkey[i+2] ^= cast_sbox7[U_INT8_Tb(z[2])];
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key->xkey[i+3] ^= cast_sbox8[U_INT8_Ta(z[3])];
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break;
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case 4:
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key->xkey[i+0] ^= cast_sbox5[U_INT8_Ta(x[2])];
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key->xkey[i+1] ^= cast_sbox6[U_INT8_Tb(x[3])];
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key->xkey[i+2] ^= cast_sbox7[U_INT8_Td(x[0])];
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key->xkey[i+3] ^= cast_sbox8[U_INT8_Td(x[1])];
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break;
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case 8:
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key->xkey[i+0] ^= cast_sbox5[U_INT8_Tb(z[2])];
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key->xkey[i+1] ^= cast_sbox6[U_INT8_Ta(z[3])];
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key->xkey[i+2] ^= cast_sbox7[U_INT8_Tc(z[0])];
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key->xkey[i+3] ^= cast_sbox8[U_INT8_Tc(z[1])];
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break;
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case 12:
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key->xkey[i+0] ^= cast_sbox5[U_INT8_Td(x[0])];
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key->xkey[i+1] ^= cast_sbox6[U_INT8_Td(x[1])];
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key->xkey[i+2] ^= cast_sbox7[U_INT8_Ta(x[2])];
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key->xkey[i+3] ^= cast_sbox8[U_INT8_Tb(x[3])];
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break;
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}
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if (i >= 16) {
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key->xkey[i+0] &= 31;
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key->xkey[i+1] &= 31;
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key->xkey[i+2] &= 31;
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key->xkey[i+3] &= 31;
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}
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}
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/* Wipe clean */
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for (i = 0; i < 4; i++) {
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t[i] = x[i] = z[i] = 0;
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}
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}
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/* Made in Canada */
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